Durán-Avendaño Yaneth Stephanie, Hernández Norge Cruz, Ruiz-Salvador A Rabdel, Abatal Mohamed
Facultad de Ingeniería, Universidad Autónoma del Carmen, Ciudad del Carmen C.P. 24155, Campeche, Mexico.
Departamento de Física Aplicada I, Escuela Politécnica Superior, Universidad de Sevilla, E-41011 Seville, Spain.
Int J Mol Sci. 2025 Apr 27;26(9):4154. doi: 10.3390/ijms26094154.
This research aims to understand the experimental results on the high selectivity of Pb removal over Cd in natural and dealuminated rich-clinoptilolite. For this purpose, we have considered the results of experimental and Density Functional Theory (DFT)-based simulated annealing (SA) on sorption of Pb and Cd from aqueous solution. The dealumination process of natural clinoptilolite (Nat-CLI) was done by HSO solutions at different concentrations (0.1-1.0 M). The results show that the maximum sorption capacity (q) of Pb and Cd varied from 224.554 × 10 to 53.827 × 10 meq/g, and between 39.044 × 10 to 20.529 × 10 meq/g, respectively, when the values of Si/Al ratio change from 4.36 to 9.50. From a theoretical point of view, the global minimum energies of natural and dealuminated clinoptilolites before and after sorption of Pb and Cd were calculated by an SA method, where heating-cooling cycles were modeled by ab initio Molecular Dynamics followed by energy minimization. The theoretical results confirmed that for all Si/Al ratios, the sorption of Pb and Cd takes place, and for dealuminated systems, the exchange energy outcomes are more favorable for the Pb cations. Since such energy differences are very small, it is not explained from a thermodynamic point of view. On the other hand, it could be understood from a kinetic perspective. In this way, we set that the atomic structural properties of the zeolite modify the first hydration coordination sphere of metal cations.
本研究旨在了解天然和脱铝富斜发沸石对铅的去除选择性高于镉的实验结果。为此，我们考虑了基于实验和密度泛函理论（DFT）的模拟退火（SA）对水溶液中铅和镉吸附的结果。天然斜发沸石（Nat-CLI）的脱铝过程通过不同浓度（0.1 - 1.0 M）的HSO溶液进行。结果表明，当硅铝比从4.36变化到9.50时，铅和镉的最大吸附容量（q）分别从224.554×10变化到53.827×10 meq/g，以及从39.044×10变化到20.529×10 meq/g。从理论角度来看，通过SA方法计算了天然和脱铝斜发沸石在吸附铅和镉前后的全局最小能量，其中加热 - 冷却循环通过从头算分子动力学建模，随后进行能量最小化。理论结果证实，对于所有硅铝比，铅和镉的吸附都会发生，并且对于脱铝体系，交换能结果对铅阳离子更有利。由于这种能量差异非常小，从热力学角度无法解释。另一方面，从动力学角度可以理解。通过这种方式，我们认为沸石的原子结构性质改变了金属阳离子的第一水合配位球。
